Pertussis, commonly called whooping cough, is a very contagious disease. It is caused by a bacterium (germ) that attacks the upper respiratory tract after entering the nose or throat. Pertussis is usually mild in older children and adults, but it can cause serious problems in very young children (i.e., infants under 1 year of age). Pertussis can be serious, especially for infants. It can cause breathing problems (apnea), pneumonia, and swelling of the brain (encephalopathy), which can lead to seizures and brain damage. Pertussis can also cause death (rarely), especially in very young infants.

Persons of any age can get pertussis, however, young infants are at greatest danger of getting the disease and suffer the most serious complications. In the past, most cases occurred in children less than 5 years of age. Recently, more cases are also being reported among adolescents and adults. Pertussis most often affects persons without any pertussis vaccination, those persons with incomplete vaccinations, and those older persons who were previously immunized as children.

Transmission occurs from person to person when germs pass from an infected person into the nose or throat of others. Pertussis can be transmitted by direct contact or through the air. Pertussis is highly infectious (easy to spread) and can infect up to 70 - 100% of close household contacts who have not received all of their vaccinations.

Older children or adults often have no symptoms or will only have mild symptoms such as a nagging cough. These older persons with infectious pertussis can transmit to other unprotected persons, especially infants.

The symptoms of pertussis occur in phases. The first phase, which lasts one to two weeks, is usually with mild upper respiratory symptoms (cold like symptoms with occasional mild cough). During the second phase, which lasts one to six weeks, the cough can progress to severe spasms often with the characteristic respiratory whoop, followed by vomiting. Fever is minimal. Older children and adults may have persistent cough with no whoop. During the third phase, which can last for several months, there is gradual reduction of the coughing spasms. Generally, the duration of pertussis is six to 10 weeks with more than half of the cases lasting less than six weeks.

The first cold-like symptoms usually occur five to 10 days, or up to 21 days, following exposure to an infected person. During this time, few people suspect that the cold symptom or mild cough is pertussis, yet they are highly infectious to others.

Pertussis is usually diagnosed by a doctor, based on history of symptoms, a physical examination, and supporting laboratory tests. Two common lab procedures used are culture tests using bacteria specimens taken from the nose or throat and blood tests. Laboratory tests are often necessary for pertussis because other germs can produce somewhat similar symptoms.

There is no cure for pertussis. Antibiotics are given to help prevent the spread of pertussis from respiratory secretions to others, and if started early enough, can also help to make the disease less severe. Antibiotics are usually taken for at least 14 days. Close contacts to pertussis cases, regardless of pertussis vaccination status, need to receive antibiotics and perhaps receive a booster dose of a pertussis-containing vaccine. Patients and contacts need to be under the care of a doctor.

A person with pertussis can be infectious (spread the disease) from five days after first exposure up to 21 days after the severe coughing spasms begin. Persons are also infectious during the cold-symptom phase of the disease before they realize they have pertussis.

Children or other persons with pertussis, or their unprotected contacts, should be excluded from school or other settings where people congregate, for up to 14 days after exposure. They can usually return to school / work after taking physician prescribed antibiotics for five consecutive days.

The best way to prevent pertussis is to ensure that children receive the recommended vaccines to prevent this disease. Persons with pertussis should be isolated from other persons. After close contact exposure to an infected person, some protection may result if 14 days of antibiotics are quickly begun. Currently licensed vaccines containing pertussis are not administered to persons after their seventh birthday.

All children should receive a series of five doses of a vaccine containing pertussis such as Diphtheria, Tetanus, and acellular Pertussis vaccine (DTaP); Diphtheria, Tetanus, and acellular Pertussis vaccine (DTP); or combinations of other vaccines that contain DTaP or DTP.

Most people have no serious reactions to this vaccine. Vaccines containing pertussis (DTaP or DTP) can cause temporary mild side effects such as a sore arm or leg, fever, fuzziness, and tiredness. This vaccine rarely causes temporary but more serious reactions such as excessive crying, very high fever, and limpness. Very rarely these vaccines can cause breathing difficulty or shock, long seizure, coma, or loss of consciousness. Generally, using DTaP vaccine will reduce the likelihood of reactions in children.